No abstract

In Indonesia, the largest mercury pollution comes from artisanal and small-scale gold mining (ASGM), which may cause the distribution of mercury to agricultural land and can be absorbed by food crops. Sukabumi Regency in West Java, well-known as one hotspot of illegal artisanal gold mining and national rice producer, is potentially threatened by mercury pollution. Efforts to remediate mercury contaminated agricultural land can be done by using mercury-reducing bacteria. This research aims to select the most potential indigenous bacteria for mercury remediation. Soil and sludge samples were collected from 2 districts in Sukabumi, where gold processing using mercury is common. Bacteria were selectively isolated from cultured colonies grown in Luria Bertani broth supplemented with HgCl2 30 mg/L. We obtained 27 isolates that belong to 16 species, as identified by API® 20 E and 20 NE (BioMérieux, USA). The growth of each isolate was assessed by measuring the optical density of inoculated LB broth contained HgCl2 30 mg/L for 5 consecutive days. All isolates showed normal growth. The log phase reached its maximum value on the second or third day after inoculation and lag phase afterward. Twelve identified isolates were chosen for evaluation of their resistance to mercury by growing them in Mueller-Hinton agar supplemented with HgCl2 (30 mg/L, 50 mg/L, 100 mg/L, 150 mg/L, and 200 mg/L). Seven isolates were able to grow in media with HgCl2, but only Mer07 survived on HgCl2 150 mg/L.

The water quality of the Sunter River in Jakarta was classified as heavily polluted due to activities around the river, both domestic and non-domestic. As one of the environmental parameters for water quality, the presence of Escherichia coli (E. coli) is normally found any natural environment, and under certain conditions it can become resistant to antimicrobials due to genetic mutations. The mutated E. coli produces Extended Spectrum Beta-Lactamase (ESBL) enzymes and has a higher survival ability in antibiotic-contaminated river water, thus potentially endangering public health. This study was aimed to evaluate the effect of environmental factors on the abundance of ESBL producing E. coli and their resistance to antibiotic cefotaxime. Sampling was conducted in six locations representing the upstreams and the downstreams of Sunter River, following the Global Surveillance guidelines. E. coli strains were isolated using Tryptone Bile X-glucuronide (TBX) agar medium (with and without the addition of cefotaxime 4μg/ml) and the antibiotic sensitivity test of ESBL E. coli was conducted by performing a double-disk test. The results showed that the highest average abundance of ESBL E. coli was found in the sample taken from Sindang Station (904.24 x 104 colony per unit (CFU) / 100 mL) and the lowest was from Sunter Station (1,58 x 104 CFU / 100 mL). The results of the Bivariate Pearson correlation analysis showed that temperature, pH, and salinity were negatively correlated with the abundance of ESBL-producing E. coli bacteria.

Microplastics are small plastic particles less than five millimeters in size. Microplastic is dangerous because it becomes a medium for other pollutants such as heavy metals and harmful bacteria to attach on. This study aims to determine the presence of microplastic in the digestive tracts of fishes in Jakarta Bay. The number of fish samples obtained was 25 fishes consisting of several species, namely, Siganus sp., Albula forsteri, Lutjanus sp., Parastromateus sp., Plicofollis argyropleuron, Pampus argenteus, Paraplotosus albilabris, Sardinella fimbriata, and Platycephalus indicus. The samples were grouped into three categories based on the length of their body, namely small fish with a length of 13-24 cm, medium fish 25-36 cm, and large fish 37-90 cm. The method used to identify microplastics in the fishes digestive tract is optical microscopy. Microplastics were found in 19 fish (76%), those identified as fiber is 73%, identified as films is 18%, and identified as fragment 9%. The larger the size of fish the higher the microplastic content of all types. This implies that microplastic bioaccumulation occurs through the food chain.

The study was conducted to investigate the growth of mercury-resistant bacterial consortium under the influence of different pHs, temperatures, and C:N ratios, as a part of mercury bioremediation research. The consortium consisted of five bacterial isolates selected due to their resistance to HgCl2 up to 100 ppm and was proven to effectively reduce mercury from the culture media. Consortium suspension was inoculated into two sets of media: 1) Tryptic soy broth (TSB) with pHs of 4.8, 6.1, 8.5, and 9.7; 2) Mineral salt with the addition of glucose and peptone to create C:N ratios of 20:1, 30:1, and 40:1 while the pH was set to 7.4. For comparison, a solution containing mercury-contaminated soil was added to the same set of media and regarded as a microbial community. The growth curves show that the bacterial consortium tended to grow better compared to the microbial community, especially in the TSB medium at incubation temperatures of 20 and 35 °C. In the same medium at a temperature of 45 °C, the growth of both consortium and community under high pHs (8.5 and 9.7) was higher than the one under lower pHs (4.8 and 6.1). Meanwhile, in the mineral salt medium, the influence of the inoculant was not remarkable except under an incubation temperature of 35 °C. Moreover, the C:N ratio did not affect the growth of either the bacterial consortium or the microbial community (p > 0.05). The variance analysis also indicated that the growths were significantly different only when the pH was 4.8.